The purpose of this proposal is primarily directed toward an understanding of suprathreshold auditory behavior among normal listeners and patients with a variety of sensorineural hearing loss. Two specific areas of investigations are described. In the first, loudness discomfort levels (LDL) and speech discrimination performance in the LDL range will be investigated among several groups of patients with well-diagnosed types of sensorineural impairments for possible clinical utility in selecting appropriate amplification systems. In the second series of investigations, the frequency selectivity properties of normal and pathological auditory systems will be explored at suprathreshold intensities. A series of experiments have been designed to measure the frequency selectivity of the auditory system from psychoacoustic auditory masking procedures and from measurements of the stapedius reflex thresholds for stimuli which vary in bandwidth and waveform. BIBLIOGRAPHIC REFERENCES: Dirks, D. and Kamm, C. Psychometric Functions for Loudness Discomfort and Most Comfortable Loudness Levels. J.S.H.R. 19, 613-627, 1976. Morgan, D., Gilman, S. and Dirks, D. Temporal Integration at the "Threshold" of the Acoustic Reflex. Accepted for publication in Journal of Acoustical Soc. of Amer., 1977.